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Operating the 60-inch Telescope Echelle Spectrograph

Echelle Spectrum
The echelle has an easy-to-use "realtime system" interface that controls telescope pointing, detector control, and file names.

common commands used to take exposures and view data:

 cex    takes a 30-sec exposure named Th-Ar
 z     "zgo;ret guide;fresh"       starts and exposure, starts guider
 s     "dmove;l+r;smooth 3;ep 0 1700"    reads out buffer and displays
 lr    "dmove; erase; lrplot 0 1700"  reads and displays both sides of the reticon 
 a     "dmove;l-r;smooth 5;ep 0 1700"
 p     "l+r;smooth 5;ep 0 1700"
 o     "l+r;smooth 5;plot 0 1700"   overplots file
 sac   "ret stop ; ret abort; ret clear; ret stop ; ret abort; ret clear"
 rfile x   reads file #x
 comment  pops up the comment editor for information stored in the file headers


Creation -- 03/22/94 by Steve Muscarella
Upgrade to HTML -- 09/11/94 by Ted Groner
Last Modified 06/27/99 by Ted Groner


    Open the dome (switch by door). Open all mirror doors (insure all covers are secured in open position). Note: See Dome instructions for complete operating and troubleshooting procedures.


    Boot the TCS-PC if necessary. The 60" TCS program will automatically be loaded. See the TCS-PC users instructions.


    Type "goechelle" on the SUN. In the dome, insert the TH-AR lamp and turn the rear switch "ON" and the front switch "OFF". Pull the dark-slide out and secure in place. Insure that the TH-AR lamp is functioning properly. Recommended procedure: Set lamp "ON" and mirror "ON" (in place). Type "cex" to start comparison exposure. View file using "show filenumber".


    Boot the guide pc if necessary. Select ECHELLE. This program does more than autoguide for ECHELLE. It also controls the dome tracking, and sends counts to the hand-held terminal in the dome.. Toggle communications ON and turn dome tracking ON. With the telescope stowed, the dome should move to AZ = 90, and be open to due east.

    Note: If guide PC is on, but only the DOS prompt ( c:\> ) is visible, just type "autoexec" and ENTER, then select "echguide" from menu to start the echelle guide program. See 60" Guider instructions for more information.

    Note: The echelle autoguider does not work well with bright stars that have over 1000cps. Use "ret noguide" to turn off autoguider. Or do not turn the autoguider on when starting an exposure (use "zgo; fresh" instead of "z")


    Make sure that the TCS RA and DEC indicators are solid blue, and NOT flashing red before turning on the rack. These indicators are located on the TCS-PC monitor. If the indicators are flashing red and not blue the telescope could run away! If the indicators are flashing red, hit F9 a few times on the TCS-PC keyboard. Turn on switch 2 (wait for delay), then 3, and 4 on front of rack located in chart room. See 60" Rack instructions for more information.

  • 6: The following are useful commands for a routine night of observing:
      z                - the most commonly used command to start an exposure.
                         "z" is an alias for "zgo; fresh; ret guide"  This
                         will start an exposure, update the comments, and start
                         the autoguider.  During the exposure you will need to
                         set the exposure time with "total x" or "mtotal y".  At
                         the end of the exposure the autoguider is automatically
                         turned off.
      ret guide        - will start the autoguider
      ret noguide      - will turn off the autoguider
                         (Note:  it is not necessary to issue any guide commands
                         directly from the guide pc.  Autoguiding for the echelle
                         is controlled though the rtshell window)
      cex              - starts a comparison exposure (lamp "ON" and mirror
                         "ON" before start of comparison exposure)
      comment          - opens comment editor for updating comment fields
      dmove            - reads out current working buffer into memory
                         (data can then be plotted; see plot commands)
      dlink (arg)      - link to directory "arg",  "arg" can be 'now' for
                         present directory, 'past' for yesterdays directory
                         or yyyy/mm/dd to select directory by date.
      ep               - erases present plot (if any) and diplays new plot
      ep n1 n2         - erase and plot from 'n1' to 'n2' are a range of
                         pixels to be plotted.  ex. ep 900 1200,  plots
                         portion from 900 to 1200 pixels
      erase            - erases present plot
      fresh            - use previous comments for new file
      goflat n         - starts a 'n' second exposure named FLAT
                         Note: goflat with no argument starts an infinite
                         exposure and MUST be followed by a total command!
      l+r              - adds left and right array counts
      l-r              - subtracts right counts from left counts
      lrplot           - plots left and right arrays separately
      mtotal m         - starts an exposure for 'm' minutes.  This can be
                         used to end an infinite exposure which was started
                         via "zgo" or "goflat"
      object obj       - updates the object field to 'obj' 
      plot n1 n2       - plot working buffer from pixels n1 to n2
      rfile (num)      - read or recover file number (num) 
      +file (num)      - add file (num) to working buffer.  May be used to
                         add two 20 minute exposures of object together
                         for equivalent of 40 minute exposure. 
      smooth n         - smooths the desired plot 'n' times.  
      zgo              - starts an exposure of infinite length.  Must stop
                         this exposure with "mtotal m" or "total n"
      backup (-dat)    - starts the backup routine. If no arg the backup
                         is to the Exabyte 9mm tape drive. If -dat, backup
                         uses the Dat 4mm tape drive.  (use this in an xterm window).
      alias            - gives entire list of aliases that already exist
      alias name       - shows contents of alias 'name' if 'name' exists
      alias foo bar    - create an alias foo that does bar.
                         a single command needs no quotes
                         ex.  alias s ret stop
                         multiple commands need quotes and separators (;)
                         ex.  alias sac "ret stop;ret abort;ret clear"
                         NOTE: all aliases will be lost on exiting unless
                               made permanent by adding to a rtrc file,
                               ~/.echelle.rtrc for echelle.

  • 7: Typical events for typical Echelle run --

      a. switch comparison mirror "ON" (top switch on box next to console)
      b. set TH-AR switch "ON" (middle switch on box next to console)
      c. start a comparison exposure (type 'cex' and )
      d. when comparison is complete, turn both switches "OFF"
      e. at sunset, open dome shutters and mirror covers
      f. check RA and DEC indicators on the TCS display are steady blue
      g. turn rack on (switch 2 [wait for delay], then 3 and 4)
      h. set comparison mirror switch "ON"
      i. telescope remains at zenith (stow position)
      j. start an infinite exposure (type 'zgo' and )
      k. momentarily turn the comparison mirror switch "OFF" and check
         the number of counts.  This can be viewed on status display.
         WARNING - DO NOT turn comparison mirror "OFF" with a bright
         sky or the image tube can be damaged.  Sky should be dark 
         enough to have some stars visible.  Counts should never 
         exceed 20,000!
      l. edit the comment field (type 'object evesky'  or 'comment'
          and enter "evesky" as the object name
      m. once counts drop to 10,000 they will begin dropping rapidly.
      n. when counts reach 5,500 -
           end the infinite exposure (zabort)
           do a 2 minute exposure (total 120) ex:  zabort; total 120
           do a comparison exposure (steps a thru d)
           slew telescope 3 hours west (+3 hours via the TCS window)
           do a comparison (steps a thru d)
           start a two minute exposure (total 120)
           update comment field with previous name (fresh)
           ex:  total 120; fresh
      o. on TCS window - enter coordinates of object, or select catalog entry
           slew telescope to object
           insure object is correct (per finding charts)
           do a comparison exposure (steps a thru d)
           start an infinite exposure ex: z 
           monitor counts using show until requested level is reached
           when it appears that enough counts will be reached by the
           next whole minute --
           set the exposure time to end by next minute
           ex: mtotal m   (m is total time, in minutes, from
           start [when z was entered] until the next whole minute)
           do a comparison exposure (steps a thru d)
           enter and slew to next object and repeat step s
           Note: the echelle autoguider does not work well with bright
           stars that have over 1000cps.  Use "ret noguide" to turn off
      p. just prior to sunrise, do the dawn sky -
           slew telescope 3 hours east (-3 hours via the TCS window)
           do a comparison exposure (steps a thru d)
           start an infinite exposure (zgo)
           when counts rise to 2500, end the infinite exposure and
           begin a 2 minute exposure ex: zabort; total 120
           do a comparison exposure (steps a thru d)
           slew the telescope to zenith (stow position)
           do a comparison exposure (steps a thru d)
           start a 2 minute exposure (total 120)
           do a comparison exposure (steps a thru d)
      q. begin shutdown procedure:
           rack power off (switches 3 and 4 then switch 2)
           home dome on guide computer
           turn mirror switch "ON"
           close mirror covers
           close dome shutters
           turn guide camera high voltage and power "OFF"
           install incandescent lamp and turn "ON"
      r. do three flats - (goflat 3600; repeat 2)
      s. insert dat tape in drive and type "backup -dat"

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